G-Protein coupled receptors mediate intercellular signaling by a cast array of neurotransmitters, modulators an hormones. they provide sites at which drugs can be used to modulate signaling in particular pathways and an entrance into study of the physiology of the system in which they are functional links. A recently identified subfamily of G-protein coupled receptors (referred to as the secretin-VIP family based on two initially identified members) has virtually no identifiable amino acid sequence conservation with the majority of G-protein coupled receptors (the rhodopsin family). Much less is known about structure-function relationships and effector system coupling of the secretin-VIP family receptors. their cloning has also raised new questions about their physiological roles and created tools for study of their distribution, regulation and pharmacology. We used degenerate PCR Primers based on sonserved sequences in the receptors for secretin, VIP and PTH to screen nervous system derived cDNA libraries for related sequences. Previously we identified the receptor for GIP and a second VIP receptor (the VIP2 receptor) which appears to mediate VIP's effects in the thalamus, Hypothalamus, and several peripheral organs including the pituitary and thus be the neuroendocrine VIP receptor. We have now identified a new parathyroid hormone receptor which is highly selective in its ligand recognition properties and quite circumscribed in distribution